/*

 * Licensed to the Apache Software Foundation (ASF) under one

 * or more contributor license agreements.  See the NOTICE file

 * distributed with this work for additional information

 * regarding copyright ownership.  The ASF licenses this file

 * to you under the Apache License, Version 2.0 (the

 * "License"); you may not use this file except in compliance

 * with the License.  You may obtain a copy of the License at

 *

 *     http://www.apache.org/licenses/LICENSE-2.0

 *

 * Unless required by applicable law or agreed to in writing, software

 * distributed under the License is distributed on an "AS IS" BASIS,

 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

 * See the License for the specific language governing permissions and

 * limitations under the License.

 */

package com.bff.gaia.unified.runners.gaia;



import com.bff.gaia.unified.sdk.Pipeline;

import com.bff.gaia.unified.sdk.values.PCollection;



/**

 * The role of this class is to translate the Unified operators to their Gaia counterparts. If we have

 * a streaming job, this is instantiated as a {@link GaiaStreamingPipelineTranslator}. In other

 * case, i.e. for a batch job, a {@link GaiaBatchPipelineTranslator} is created. Correspondingly,

 * the {@link PCollection}-based user-provided job is translated into a

 * {@link com.bff.gaia.streaming.api.datastream.DataStream} (for streaming) or a {@link

 * com.bff.gaia.api.java.DataSet} (for batch) one.

 */

abstract class GaiaPipelineTranslator extends Pipeline.PipelineVisitor.Defaults {



  /**

   * Translates the pipeline by passing this class as a visitor.

   *

   * @param pipeline The pipeline to be translated

   */

  public void translate(Pipeline pipeline) {

    pipeline.traverseTopologically(this);

  }



  /**

   * Utility formatting method.

   *

   * @param n number of spaces to generate

   * @return String with "|" followed by n spaces

   */

  protected static String genSpaces(int n) {

    StringBuilder builder = new StringBuilder();

    for (int i = 0; i < n; i++) {

      builder.append("|   ");

    }

    return builder.toString();

  }

}